Fix for Oracle VBCS "Error 404--Not Found"

We are using Pay As You Go Oracle VBCS instance and had an issue with accessing VBCS home page after starting the service. The service was started successfully, without errors. But when accessing VBCS home page URL - "Error 404--Not Found" was returned.

I raised a support ticket and must say - received the response and help promptly. If you would encounter similar issue yourself, hopefully, this post will share some light.

Apparently "Error 404--Not Found" was returned, because VBCS instance wasn't initialized during instance start. It wasn't initialized, because of expired password for VBCS DB schemas. Yes, you read it right - internal system passwords expire in Cloud too.

Based on the instructions given by Oracle Support, I was able to extract logs from VBCS WebLogic instance (by connecting through SSH to VBCS cloud machine) and provide it to support team (yes, VBCS runs on WebLogic). They found password expire errors in the log, similar to this:

weblogic.application.ModuleException: java.sql.SQLException: ORA-28001: the password has expired

Based on provided instructions, I extracted VBCS DB schema name and connected through SQL developer. Then I executed SQL statement given by support team to reset all VBCS DB passwords in bulk. Next password expiry is set for 2019/January. Should it expire at all?

Summary: If you would encounter "Error 404--Not Found" after starting VBCS instance and trying to access VBCS home page, then most likely (but not always) it will be related to VBCS DB schema password expiry issue.

Forecast Model Tuning with Additional Regressors in Prophet

I’m going to share my experiment results with Prophet additional regressors. My goal was to check how extra regressor would weight on forecast calculated by Prophet.

Using dataset from Kaggle — Bike Sharing in Washington D.C. Dataset. Data comes with a number for bike rentals per day and weather conditions. I have created and compared three models:

1. Time series Prophet model with date and number of bike rentals
2. A model with additional regressor —weather temperature
3. A model with additional regressor s— weather temperature and state (raining, sunny, etc.)

We should see the effect of regressor and compare these three models.

Read more in my Towards Data Science post.

Oracle ADF A Status Update

Oracle posted information update for Oracle ADF - "With the continuous investment and usage of Oracle ADF inside Oracle we expect external customers will also continue to enjoy the benefits of Oracle ADF for many more years."

Read the complete post here: https://blogs.oracle.com/jdeveloperpm/oracle-adf-a-status-update

Happy to read the update, sounds positive. Thanks to Oracle for taking time and publishing this information. #adf #middleware #javascript #oracle #cloud #oraclefusion

Serving Prophet Model with Flask — Predicting Future

The solution to demonstrate how to serve Prophet model API on the Web with Flask. Prophet — Open-Source Python library developed by Facebook to predict time series data.

An accurate forecast and future prediction are crucial almost for any business. This is an obvious thing and it doesn’t need explanation. There is a concept of time series data, this data is ordered by date and typically each date is assigned with one or more values specific to that date. Machine Learning powered models could generate forecasts based on time series data. Such forecasts could be an important source of information for business decisions.

Read more in my Towards Data Science post.

Oracle Developer Tools - Do They Still Exist?

People are frustrated about @OracleADF @JDeveloper on social media - "ADF boat has no captain", etc. I agree @Oracle is to blame big time for such lame handling of its own Developer Tools stack. @Oracle please wake up and spend some budget on @OracleADF. Read more:

Oracle VBCS - right now this tool gets the most of Oracle focus. Supposed to offer declarative #JavaScript development experience in the Cloud. Not well received by the community. Are there any VBCS customers, please respond if yes?

Oracle APEX - comes with a very strong community (mostly backed by DB folks). But is not strategic for Oracle. More likely will be used by PL/SQL guys then by Java or Web developers. 

Oracle JET - highly promoted by Oracle. Set of opensource #JavaScript libs, glued by Oracle layer. Nice, but can't be used as a direct replacement for @OracleADF, JET is UI layer only. Oracle folks often confuse community by saying - Oracle JET is a great option to replace ADF

Oracle Forms - still alive, but obviously can't be strategic Oracle platform. A few years ago, Oracle was promoting Forms modernization to @OracleADF

Summary - Oracle Developer tools offering is weak. Lack of Oracle investment into development tools - makes Oracle developers community shrink.

Running Oracle JET as Progressive Web App

Progressive Web Apps (PWA) topic is a hot thing in web development these days. Read more about it - Progressive Web Apps. The beauty and power behind PWA - user can install a web app to his mobile device, without going through the app store. This simplifies update process too, when a new version of the app is available, the user will get it straight away, because it is essentially a Web page, wrapped to look like an installed app.

Inspired by this post - A Simple Progressive Web App Tutorial, I decided to add PWA config into Oracle JET app and test how it works (on Android, didn't test on iOS, but there is nothing JET specific, if PWA is supported on iOS, it should work).

Oracle JET PWA sample app is deployed on Heroku (PWA will work only if the app is coming through HTTPS) and available under this URL. The sample app is available on GitHub repo. Node.js wrapper for this sample is available in another GitHub repo, you can use it to deploy on Heroku or another service.

Access JET app URL, the app will be loaded and you should see Android notification in the bottom. Google Chrome mobile browser automatically is recognizing PWA app by manifest and offers to "install" it by adding to the home screen:

Select notification and you will get a confirmation message:

Select "Add" and Web app will be added to the home screen. It will look like a real mobile app for the user. For example, the user could get runtime stats for the app, check storage and data usage metrics:

The app is added to the home screen (look for Oracle  JET icon):

Select the app icon and app will be opened. There is no URL address bar in the header and indeed it looks like a mobile app, not a Web page:

The app will be recognized as PWA, if certain config steps were implemented. One of them - you need to add manifest file (add it in Oracle JET in the same folder as index.html) and provide app icons, name, etc.:

The manifest file must be included through a reference in the app entry point - index page (Oracle JET index.html page for example):

In addition to manifest, the app must define a service worker (same as manifest file, you can create this file in the same directory as Oracle JET index.html). PWA doesn't only bring the visual experience of the real app to the Web application. You can define a cache store for the app files, this means next time when offline - app files will load from local cache storage, there will be no need to download them from the internet:

Service worker can be registered from main.js file where Oracle JET context is initialized on the application initial load. Add service worker registration at the bottom of main.js:

The idea of this post was to share a simple example of PWA for Oracle JET. This should help you to get started quickly with PWA support config for Oracle JET app.

Running Oracle JET on Heroku with Node.js (JET Showcase)

I have implemented JET (more about Oracle JET) showcase app with data visualization components usage. This app shows historical weather data in Boston city, the dataset is taken from Kaggle. Switching years makes data visualization to change and show new data - I love how polar chat is updated. Calendar displays temperature for each day during the year using JET picto chart component:

App is deployed on Heroku and available by this URL. Heroku provides $7 per month account with analytics and better resources, but there is a free option too (it comes with sleep after 30 minutes of inactivity) - free option is good for experimentation, as for this case.

Heroku dashboard for the deployed JET app:

Free deployment comes without analytics option:

App comes with two options - Dashboard and Histogram. The dashboard allows switching between years and shows a polar chart along with daily temperature calendar:

The histogram displays the same data in a different view:

This app comes with Web Component implementation, yes Web Components are a standard feature in JET. Toolbar, where you can switch years, is implemented as Web Component:

Web Component is being used in both UIs - dashboard and histogram:

Visualization components are getting data through Knockout.JS observable variables:

Variables are initialized in JS functions:

Resources:

1. Heroku deployment guide for Node.js
2. Node.js app which is deployed on Heroku - GitHub. JET content is inside the public folder. JET content is copied from JET app web folder, after running ojet build --release
3. Oracle JET app - GitHub